1. Field of the Invention
The present invention relates generally to the art of producing a water-repellent film on various substrates, and more particularly, to improving the durability of such water-repellent films. The durability is improved by modifying the surface of the substrate to expose a plurality of bonding sites on the surface of the substrate, which bonding sites react with the water-repellent film to more effectively bond the film to the substrate, thereby improving the durability of the water-repellent film.
In addition to or in lieu of the foregoing, the durability of the water-repellent film may also be improved by controlling certain process and environmental conditions under which the water-repellent film is deposited over the surface of the substrate.
2. Relevant Art
U.S. Pat. No. 4,997,684 to Franz et al. discloses a method for providing a durable nonwetting surface on glass by contacting the glass with a perfluoroalkylalkyl silane and a fluorinated olefin telomer and heating the glass to produce a durable non-wetting surface.
U.S. Pat. No. 5,328,768 to Goodwin discloses a technique for producing a durable non-wetting surface on a glass substrate, wherein the surface of the substrate is cleaned with a water and 50/50 by volume isopropanol/water solution. The surface is then treated with a silica primer layer and a perfluoroalkylalkyl silane over the primer layer. The silica primer layer improves the durability of the water repellency of the surface.
U.S. Pat. No. 5,523,162 to Franz et al. discloses a method for producing a durable non-wetting surface on a plastic substrate, herein the surface of the plastic substrate is cleaned with hexane and then methanol. The surface is then treated with a silica primer layer and a perfluoroalkylalkyl silane.
U.S. Pat. No. 5,674,967 to Goodwin discloses compositions for producing water-repellent surfaces on a substrate which include perfluoroalkylalkyl silane and compounds selected from silanes and siloxanes capable of hydrolysis to a silica gel.
U.S. Pat. No. 5,688,684 to Goodwin discloses a composition for producing a non-wetting surface on a substrate comprising a perfluoroalkylalkyl silane in aprotic solvents which limit the evaporation of the solvent during application of the composition to the surface of the substrate.
U.S. Pat. No. 5,693,365 to Teranishi et al. discloses a method for forming a water-repellent film on the surface of a transparent substrate (e.g., sheet glass). While the film on the coated substrate is dried, the temperature is controlled to fall between 15.degree. C. and 25.degree. C., the relative humidity is controlled to be 30% or preferably from 15% to 20%, and the speed of the air stream to be applied to the coated substrate is controlled to be 0.5 m/min. or lower.
While the foregoing U.S. patents disclose durable water-repellent films, it can be appreciated by those skilled in the art that making available additional technology to improve the durability of the water-repellent surface is advantageous and desirable.